I was recently helping a guy get some better camera angles at a live performance in a record store, and I have a Nikon d5100 and he has a Canon crop-sensor camera, but I can't remember what it was called. There was not a lot of light available. He had an 85mm 2.0 and I had a 35mm 1, 8. We both shot at 30fps 1080p and similar exposure.
But his video looked almost perfectly clean while mine had noticeable noise. I don't know if he's going to be able to use it. Why is this the case for video? According to DXOmark, the Nikon d5100 has the best low light ISO capability of any APS-C camera except 1 Pentax one and most of the Canon ones are much less capable, so it must be exclusively a video thing.
Added (1). My lens was not stopped down or anything, it was at 1.8. Also, when I said 30fps, what I meant to say was shutter speed of 30, 25fps.
I'm looking back over the video comparisons and it's not actually as different as I remember, but it is still there.
As for what my ISO was set to, I can't say because on the d5100, the ISO setting doesn't affect live view at all, which is always set to auto-ISO, but I had my exposure set to -0.3 to give the right lowish lighting look and all my settings locked in manual.
Added (2). I know about the aperture bug in live view. I changed it before I changed to live view.
>>> Why is Nikon video poorer in quality than Canon? - 1